I'm not really up on all the terminology, but the Bujin bags are made out of cordura, or maybe it's what they're all calling "ballistic" fabric nowadays, whatever that means. It's a synthetic of a particular weave and durability, is all. "Nylon" is, of course, a much broader term. The Bujin bags are really hard to beat in terms of the quality of materials and workmanship...if you can find something comparable, don't hesitate.